// Copyright (c) Pomelo Foundation. All rights reserved.
// Licensed under the MIT. See LICENSE in the project root for license information.

using System;
using System.Data;
using System.Data.Common;
using System.Collections;
using Pomelo.Data.Types;
using System.Collections.Generic;
using System.Globalization;
using Pomelo.Data.Common;
using Pomelo.Data.MySql;
using System.Threading;

namespace Pomelo.Data.MySql
{
    /// <include file='docs/MySqlDataReader.xml' path='docs/ClassSummary/*'/>
    public sealed partial class MySqlDataReader : IDisposable
    {
        // The DataReader should always be open when returned to the user.
        private bool isOpen = true;

        private CommandBehavior commandBehavior;
        public MySqlCommand command;
        internal long affectedRows;
        internal Driver driver;
        private PreparableStatement statement;
        private ResultSet resultSet;

        // Used in special circumstances with stored procs to avoid exceptions from DbDataAdapter
        // If set, AffectedRows returns -1 instead of 0.
        private bool disableZeroAffectedRows;

        /* 
         * Keep track of the connection in order to implement the
         * CommandBehavior.CloseConnection flag. A null reference means
         * normal behavior (do not automatically close).
         */
        private MySqlConnection connection;

        /*
         * Because the user should not be able to directly create a 
         * DataReader object, the constructors are
         * marked as internal.
         */
        internal MySqlDataReader(MySqlCommand cmd, PreparableStatement statement, CommandBehavior behavior)
        {
            this.command = cmd;
            connection = (MySqlConnection)command.Connection;
            commandBehavior = behavior;
            driver = connection.driver;
            affectedRows = -1;
            this.statement = statement;

#if !RT
            if (cmd.CommandType == CommandType.StoredProcedure
              && cmd.UpdatedRowSource == UpdateRowSource.FirstReturnedRecord
            )
            {
                disableZeroAffectedRows = true;
            }
#endif
        }

        #region Properties

        internal PreparableStatement Statement
        {
            get { return statement; }
        }

        internal MySqlCommand Command
        {
            get { return command; }
        }

        internal ResultSet ResultSet
        {
            get { return resultSet; }
        }

        internal CommandBehavior CommandBehavior
        {
            get { return commandBehavior; }
        }

        /// <summary>
        /// Gets the number of columns in the current row.
        /// </summary>
        public override int FieldCount
        {
            get { return resultSet == null ? 0 : resultSet.Size; }
        }

        /// <summary>
        /// Gets a value indicating whether the MySqlDataReader contains one or more rows.
        /// </summary>
        public override bool HasRows
        {
            get { return resultSet == null ? false : resultSet.HasRows; }
        }

        /// <summary>
        /// Gets a value indicating whether the data reader is closed.
        /// </summary>
        public override bool IsClosed
        {
            get { return !isOpen; }
        }

        /// <summary>
        /// Gets the number of rows changed, inserted, or deleted by execution of the SQL statement.
        /// </summary>
        public override int RecordsAffected
        {
            // RecordsAffected returns the number of rows affected in batch
            // statments from insert/delete/update statments.  This property
            // is not completely accurate until .Close() has been called.
            get
            {

                if (disableZeroAffectedRows)
                {
                    // In special case of updating stored procedure called from 
                    // within data adapter, we return -1 to avoid exceptions 
                    // (s. Bug#54895)
                    if (affectedRows == 0)
                        return -1;

                }

                return (int)affectedRows;
            }
        }

        /// <summary>
        /// Overloaded. Gets the value of a column in its native format.
        /// In C#, this property is the indexer for the MySqlDataReader class.
        /// </summary>
        public override object this[int i]
        {
            get { return GetValue(i); }
        }

        /// <summary>
        /// Gets the value of a column in its native format.
        ///	[C#] In C#, this property is the indexer for the MySqlDataReader class.
        /// </summary>
        public override object this[String name]
        {
            // Look up the ordinal and return 
            // the value at that position.
            get { return this[GetOrdinal(name)]; }
        }

        #endregion

        /// <summary>
        /// Closes the MySqlDataReader object.
        /// </summary>
        public override void Close()
        

        {
            if (!isOpen) return;

            bool shouldCloseConnection = (commandBehavior & CommandBehavior.CloseConnection) != 0;
            CommandBehavior originalBehavior = commandBehavior;

            // clear all remaining resultsets
            try
            {
                // Temporarily change to Default behavior to allow NextResult to finish properly.
                if (!originalBehavior.Equals(CommandBehavior.SchemaOnly))
                    commandBehavior = CommandBehavior.Default;
                while (NextResult()) { }
            }
            catch (MySqlException ex)
            {
                // Ignore aborted queries
                if (!ex.IsQueryAborted)
                {
                    // ignore IO exceptions.
                    // We are closing or disposing reader, and  do not
                    // want exception to be propagated to used. If socket is
                    // is closed on the server side, next query will run into
                    // IO exception. If reader is closed by GC, we also would 
                    // like to avoid any exception here. 
                    bool isIOException = false;
                    for (Exception exception = ex; exception != null;
                      exception = exception.InnerException)
                    {
                        if (exception is System.IO.IOException)
                        {
                            isIOException = true;
                            break;
                        }
                    }
                    if (!isIOException)
                    {
                        // Ordinary exception (neither IO nor query aborted)
                        throw;
                    }
                }
            }
            catch (System.IO.IOException)
            {
                // eat, on the same reason we eat IO exceptions wrapped into 
                // MySqlExceptions reasons, described above.
            }
            finally
            {
                // always ensure internal reader is null (Bug #55558)
                connection.Reader = null;
                commandBehavior = originalBehavior;
            }
            // we now give the command a chance to terminate.  In the case of
            // stored procedures it needs to update out and inout parameters
            command.Close(this);
            commandBehavior = CommandBehavior.Default;

            if (this.command.Canceled && connection.driver.Version.isAtLeast(5, 1, 0))
            {
                // Issue dummy command to clear kill flag
                ClearKillFlag();
            }

            if (shouldCloseConnection)
                connection.Close();

            command = null;
            connection.IsInUse = false;
            connection = null;
            isOpen = false;
        }

        #region TypeSafe Accessors

        /// <summary>
        /// Gets the value of the specified column as a Boolean.
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        public bool GetBoolean(string name)
        {
            return GetBoolean(GetOrdinal(name));
        }

        /// <summary>
        /// Gets the value of the specified column as a Boolean.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public override bool GetBoolean(int i)
        {
            return Convert.ToBoolean(GetValue(i));
        }

        /// <summary>
        /// Gets the value of the specified column as a byte.
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        public byte GetByte(string name)
        {
            return GetByte(GetOrdinal(name));
        }

        /// <summary>
        /// Gets the value of the specified column as a byte.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public override byte GetByte(int i)
        {
            IMySqlValue v = GetFieldValue(i, false);
            if (v is MySqlUByte)
                return ((MySqlUByte)v).Value;
            else
                return (byte)((MySqlByte)v).Value;
        }

        /// <summary>
        /// Gets the value of the specified column as a sbyte.
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        public sbyte GetSByte(string name)
        {
            return GetSByte(GetOrdinal(name));
        }

        /// <summary>
        /// Gets the value of the specified column as a sbyte.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public sbyte GetSByte(int i)
        {
            IMySqlValue v = GetFieldValue(i, false);
            if (v is MySqlByte)
                return ((MySqlByte)v).Value;
            else
                return (sbyte)((MySqlByte)v).Value;
        }

        /// <summary>
        /// Reads a stream of bytes from the specified column offset into the buffer an array starting at the given buffer offset.
        /// </summary>
        /// <param name="i">The zero-based column ordinal. </param>
        /// <param name="fieldOffset">The index within the field from which to begin the read operation. </param>
        /// <param name="buffer">The buffer into which to read the stream of bytes. </param>
        /// <param name="bufferoffset">The index for buffer to begin the read operation. </param>
        /// <param name="length">The maximum length to copy into the buffer. </param>
        /// <returns>The actual number of bytes read.</returns>
        /// <include file='docs/MySqlDataReader.xml' path='MyDocs/MyMembers[@name="GetBytes"]/*'/>
        public override long GetBytes(int i, long fieldOffset, byte[] buffer, int bufferoffset, int length)
        {
            if (i >= FieldCount)
                Throw(new IndexOutOfRangeException());

            IMySqlValue val = GetFieldValue(i, false);

            if (!(val is MySqlBinary) && !(val is MySqlGuid))
                Throw(new MySqlException("GetBytes can only be called on binary or guid columns"));

            byte[] bytes = null;
            if (val is MySqlBinary)
                bytes = ((MySqlBinary)val).Value;
            else
                bytes = ((MySqlGuid)val).Bytes;

            if (buffer == null)
                return bytes.Length;

            if (bufferoffset >= buffer.Length || bufferoffset < 0)
                Throw(new IndexOutOfRangeException("Buffer index must be a valid index in buffer"));
            if (buffer.Length < (bufferoffset + length))
                Throw(new ArgumentException("Buffer is not large enough to hold the requested data"));
            if (fieldOffset < 0 ||
              ((ulong)fieldOffset >= (ulong)bytes.Length && (ulong)bytes.Length > 0))
                Throw(new IndexOutOfRangeException("Data index must be a valid index in the field"));

            // adjust the length so we don't run off the end
            if ((ulong)bytes.Length < (ulong)(fieldOffset + length))
            {
                length = (int)((ulong)bytes.Length - (ulong)fieldOffset);
            }

            Buffer.BlockCopy(bytes, (int)fieldOffset, buffer, (int)bufferoffset, (int)length);

            return length;
        }

        private object ChangeType(IMySqlValue value, int fieldIndex, Type newType)
        {
            resultSet.Fields[fieldIndex].AddTypeConversion(newType);
            return Convert.ChangeType(value.Value, newType, CultureInfo.InvariantCulture);
        }

        /// <summary>
        /// Gets the value of the specified column as a single character.
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        public char GetChar(string name)
        {
            return GetChar(GetOrdinal(name));
        }

        /// <summary>
        /// Gets the value of the specified column as a single character.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public override char GetChar(int i)
        {
            string s = GetString(i);
            return s[0];
        }

        /// <summary>
        /// Reads a stream of characters from the specified column offset into the buffer as an array starting at the given buffer offset.
        /// </summary>
        /// <param name="i"></param>
        /// <param name="fieldoffset"></param>
        /// <param name="buffer"></param>
        /// <param name="bufferoffset"></param>
        /// <param name="length"></param>
        /// <returns></returns>
        public override long GetChars(int i, long fieldoffset, char[] buffer, int bufferoffset, int length)
        {
            if (i >= FieldCount)
                Throw(new IndexOutOfRangeException());

            string valAsString = GetString(i);

            if (buffer == null) return valAsString.Length;

            if (bufferoffset >= buffer.Length || bufferoffset < 0)
                Throw(new IndexOutOfRangeException("Buffer index must be a valid index in buffer"));
            if (buffer.Length < (bufferoffset + length))
                Throw(new ArgumentException("Buffer is not large enough to hold the requested data"));
            if (fieldoffset < 0 || fieldoffset >= valAsString.Length)
                Throw(new IndexOutOfRangeException("Field offset must be a valid index in the field"));

            if (valAsString.Length < length)
                length = valAsString.Length;
            valAsString.CopyTo((int)fieldoffset, buffer, bufferoffset, length);
            return length;
        }

        /// <summary>
        /// Gets the name of the source data type.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public override String GetDataTypeName(int i)
        {
            if (!isOpen)
                Throw(new Exception("No current query in data reader"));
            if (i >= FieldCount)
                Throw(new IndexOutOfRangeException());

            // return the name of the type used on the backend
            IMySqlValue v = resultSet.Values[i];
            return v.MySqlTypeName;
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetMySqlDateTime/*'/>
        public MySqlDateTime GetMySqlDateTime(string column)
        {
            return GetMySqlDateTime(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetMySqlDateTime/*'/>
        public MySqlDateTime GetMySqlDateTime(int column)
        {
            return (MySqlDateTime)GetFieldValue(column, true);
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetDateTimeS/*'/>
        public DateTime GetDateTime(string column)
        {
            return GetDateTime(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetDateTime/*'/>
        public override DateTime GetDateTime(int i)
        {
            IMySqlValue val = GetFieldValue(i, true);
            MySqlDateTime dt;

            if (val is MySqlDateTime)
                dt = (MySqlDateTime)val;
            else
            {
                // we need to do this because functions like date_add return string
                string s = GetString(i);
                dt = MySqlDateTime.Parse(s);
            }

            dt.TimezoneOffset = driver.timeZoneOffset;
            if (connection.Settings.ConvertZeroDateTime && !dt.IsValidDateTime)
                return DateTime.MinValue;
            else
                return dt.GetDateTime();
        }

        public MySqlDecimal GetMySqlDecimal(string column)
        {
            return GetMySqlDecimal(GetOrdinal(column));
        }

        public MySqlDecimal GetMySqlDecimal(int i)
        {
            return (MySqlDecimal)GetFieldValue(i, false);
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetDecimalS/*'/>
        public Decimal GetDecimal(string column)
        {
            return GetDecimal(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetDecimal/*'/>
        public override Decimal GetDecimal(int i)
        {
            IMySqlValue v = GetFieldValue(i, true);
            if (v is MySqlDecimal)
                return ((MySqlDecimal)v).Value;
            return Convert.ToDecimal(v.Value);
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetDoubleS/*'/>
        public double GetDouble(string column)
        {
            return GetDouble(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetDouble/*'/>
        public override double GetDouble(int i)
        {
            IMySqlValue v = GetFieldValue(i, true);
            if (v is MySqlDouble)
                return ((MySqlDouble)v).Value;
            return Convert.ToDouble(v.Value);
        }

        public override T GetFieldValue<T>(int ordinal)
        {
            var type = typeof(T);
            if (type.FullName.IndexOf("System.JsonObject`1") >= 0)
            {
                JsonObject value = (JsonObject)GetValue(ordinal);
                return (T)Activator.CreateInstance(type, value.Json);
            }
            return base.GetFieldValue<T>(ordinal);
        }

        public Type GetFieldType(string column)
        {
            return GetFieldType(GetOrdinal(column));
        }

        /// <summary>
        /// Gets the Type that is the data type of the object.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public override Type GetFieldType(int i)
        {
            if (!isOpen)
                Throw(new Exception("No current query in data reader"));
            if (i >= FieldCount)
                Throw(new IndexOutOfRangeException());

            // we have to use the values array directly because we can't go through
            // GetValue
            IMySqlValue v = resultSet.Values[i];
            if (v is MySqlDateTime)
            {
                if (!connection.Settings.AllowZeroDateTime)
                    return typeof(DateTime);
                return typeof(MySqlDateTime);
            }
            return v.SystemType;
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetFloatS/*'/>
        public float GetFloat(string column)
        {
            return GetFloat(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetFloat/*'/>
        public override float GetFloat(int i)
        {
            IMySqlValue v = GetFieldValue(i, true);
            if (v is MySqlSingle)
                return ((MySqlSingle)v).Value;
            return Convert.ToSingle(v.Value);
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetGuidS/*'/>
        public Guid GetGuid(string column)
        {
            return GetGuid(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetGuid/*'/>
        public override Guid GetGuid(int i)
        {
            object v = GetValue(i);
            if (v is Guid)
                return (Guid)v;
            if (v is string)
                return new Guid(v as string);
            if (v is byte[])
            {
                byte[] bytes = (byte[])v;
                if (bytes.Length == 16)
                    return new Guid(bytes);
            }
            Throw(new MySqlException(Resources.ValueNotSupportedForGuid));
            return Guid.Empty; // just to silence compiler
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetInt16S/*'/>
        public Int16 GetInt16(string column)
        {
            return GetInt16(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetInt16/*'/>
        public override Int16 GetInt16(int i)
        {
            IMySqlValue v = GetFieldValue(i, true);
            if (v is MySqlInt16)
                return ((MySqlInt16)v).Value;

            return (short)ChangeType(v, i, typeof(short));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetInt32S/*'/>
        public Int32 GetInt32(string column)
        {
            return GetInt32(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetInt32/*'/>
        public override Int32 GetInt32(int i)
        {
            IMySqlValue v = GetFieldValue(i, true);
            if (v is MySqlInt32)
                return ((MySqlInt32)v).Value;

            return (Int32)ChangeType(v, i, typeof(Int32));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetInt64S/*'/>
        public Int64 GetInt64(string column)
        {
            return GetInt64(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetInt64/*'/>
        public override Int64 GetInt64(int i)
        {
            IMySqlValue v = GetFieldValue(i, true);
            if (v is MySqlInt64)
                return ((MySqlInt64)v).Value;

            return (Int64)ChangeType(v, i, typeof(Int64));
        }

        /// <summary>
        /// Gets the name of the specified column.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public override String GetName(int i)
        {
            if (!isOpen)
                Throw(new Exception("No current query in data reader"));
            if (i >= FieldCount)
                Throw(new IndexOutOfRangeException());

            return resultSet.Fields[i].ColumnName;
        }

        /// <summary>
        /// Gets the column ordinal, given the name of the column.
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        public override int GetOrdinal(string name)
        {
            if (!isOpen || resultSet == null)
                Throw(new Exception("No current query in data reader"));

            return resultSet.GetOrdinal(name);
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetStringS/*'/>
        public string GetString(string column)
        {
            return GetString(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetString/*'/>
        public override String GetString(int i)
        {
            IMySqlValue val = GetFieldValue(i, true);

            if (val is MySqlBinary)
            {
                byte[] v = ((MySqlBinary)val).Value;
                return resultSet.Fields[i].Encoding.GetString(v, 0, v.Length);
            }

            return val.Value.ToString();
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetTimeSpan/*'/>
        public TimeSpan GetTimeSpan(string column)
        {
            return GetTimeSpan(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetTimeSpan/*'/>
        public TimeSpan GetTimeSpan(int column)
        {
            IMySqlValue val = GetFieldValue(column, true);

            MySqlTimeSpan ts = (MySqlTimeSpan)val;
            return ts.Value;
        }

        /// <summary>
        /// Gets the value of the specified column in its native format.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public override object GetValue(int i)
        {
            if (!isOpen)
                Throw(new Exception("No current query in data reader"));
            if (i >= FieldCount)
                Throw(new IndexOutOfRangeException());

            IMySqlValue val = GetFieldValue(i, false);
            if (val.IsNull)
                return DBNull.Value;

            // if the column is a date/time, then we return a MySqlDateTime
            // so .ToString() will print '0000-00-00' correctly
            if (val is MySqlDateTime)
            {
                MySqlDateTime dt = (MySqlDateTime)val;
                if (!dt.IsValidDateTime && connection.Settings.ConvertZeroDateTime)
                    return DateTime.MinValue;
                else if (connection.Settings.AllowZeroDateTime)
                    return val;
                else
                    return dt.GetDateTime();
            }

            if (val is MySqlJson)
            {
                return new JsonObject(val.Value.ToString());
            }

            return val.Value;
        }

        /// <summary>
        /// Gets all attribute columns in the collection for the current row.
        /// </summary>
        /// <param name="values"></param>
        /// <returns></returns>
        public override int GetValues(object[] values)
        {
            int numCols = Math.Min(values.Length, FieldCount);
            for (int i = 0; i < numCols; i++)
                values[i] = GetValue(i);

            return numCols;
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetUInt16/*'/>
        public UInt16 GetUInt16(string column)
        {
            return GetUInt16(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetUInt16/*'/>
        public UInt16 GetUInt16(int column)
        {
            IMySqlValue v = GetFieldValue(column, true);
            if (v is MySqlUInt16)
                return ((MySqlUInt16)v).Value;

            return (UInt16)ChangeType(v, column, typeof(UInt16));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetUInt32/*'/>
        public UInt32 GetUInt32(string column)
        {
            return GetUInt32(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetUInt32/*'/>
        public UInt32 GetUInt32(int column)
        {
            IMySqlValue v = GetFieldValue(column, true);
            if (v is MySqlUInt32)
                return ((MySqlUInt32)v).Value;
            return (uint)ChangeType(v, column, typeof(UInt32));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetUInt64/*'/>
        public UInt64 GetUInt64(string column)
        {
            return GetUInt64(GetOrdinal(column));
        }

        /// <include file='docs/MySqlDataReader.xml' path='docs/GetUInt64/*'/>
        public UInt64 GetUInt64(int column)
        {
            IMySqlValue v = GetFieldValue(column, true);
            if (v is MySqlUInt64)
                return ((MySqlUInt64)v).Value;

            return (UInt64)ChangeType(v, column, typeof(UInt64));
        }


        #endregion

        /// <summary>
        /// Gets a value indicating whether the column contains non-existent or missing values.
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public override bool IsDBNull(int i)
        {
            if (!isOpen)
                Throw(new Exception("No current query in data reader"));
            if (i >= FieldCount)
                Throw(new IndexOutOfRangeException());

            IMySqlValue val = GetFieldValue(i, false);
            return val.IsNull;//原来调用 GetValue(int i)，如果是值类型，并且有值的话，会引起装箱。
        }

        /// <summary>
        /// Advances the data reader to the next result, when reading the results of batch SQL statements.
        /// </summary>
        /// <returns></returns>
        public override bool NextResult()
        {
            if (!isOpen)
                Throw(new MySqlException(Resources.NextResultIsClosed));

            bool isCaching = command.CommandType == CommandType.TableDirect && command.EnableCaching &&
              (commandBehavior & CommandBehavior.SequentialAccess) == 0;

            // this will clear out any unread data
            if (resultSet != null)
            {
                resultSet.Close();
                if (isCaching)
                    TableCache.AddToCache(command.CommandText, resultSet);
            }

            // single result means we only return a single resultset.  If we have already
            // returned one, then we return false
            // TableDirect is basically a select * from a single table so it will generate
            // a single result also
            if (resultSet != null &&
              ((commandBehavior & CommandBehavior.SingleResult) != 0 || isCaching))
                return false;

            // next load up the next resultset if any
            try
            {
                do
                {
                    resultSet = null;
                    // if we are table caching, then try to retrieve the resultSet from the cache
                    if (isCaching)
                        resultSet = TableCache.RetrieveFromCache(command.CommandText,
                          command.CacheAge);

                    if (resultSet == null)
                    {
                        resultSet = driver.NextResult(Statement.StatementId, false);
                        if (resultSet == null) return false;
                        if (resultSet.IsOutputParameters && command.CommandType == CommandType.StoredProcedure)
                        {
                            StoredProcedure sp = statement as StoredProcedure;
                            sp.ProcessOutputParameters(this);
                            resultSet.Close();
                            if (!sp.ServerProvidingOutputParameters) return false;
                            // if we are using server side output parameters then we will get our ok packet
                            // *after* the output parameters resultset
                            resultSet = driver.NextResult(Statement.StatementId, true);
                        }
                        resultSet.Cached = isCaching;
                    }

                    if (resultSet.Size == 0)
                    {
                        Command.lastInsertedId = resultSet.InsertedId;
                        if (affectedRows == -1)
                            affectedRows = resultSet.AffectedRows;
                        else
                            affectedRows += resultSet.AffectedRows;
                    }
                } while (resultSet.Size == 0);

                return true;
            }
            catch (MySqlException ex)
            {
                if (ex.IsFatal)
                    connection.Abort();
                if (ex.Number == 0)
                    throw new MySqlException(Resources.FatalErrorReadingResult, ex);
                if ((commandBehavior & CommandBehavior.CloseConnection) != 0)
#if NETFW
                    Close();
#else
                    Dispose();

#endif
                throw;
            }
        }

        /// <summary>
        /// Advances the MySqlDataReader to the next record.
        /// </summary>
        /// <returns></returns>
        public override bool Read()
        {
            if (!isOpen)
                Throw(new MySqlException("Invalid attempt to Read when reader is closed."));
            if (resultSet == null)
                return false;

            try
            {
                return resultSet.NextRow(commandBehavior);
            }
            catch (TimeoutException tex)
            {
                connection.HandleTimeoutOrThreadAbort(tex);
                throw; // unreached
            }
            catch (ThreadAbortException taex)
            {
                connection.HandleTimeoutOrThreadAbort(taex);
                throw;
            }
            catch (MySqlException ex)
            {
                if (ex.IsFatal)
                    connection.Abort();

                if (ex.IsQueryAborted)
                {
                    throw;
                }

                throw new MySqlException(Resources.FatalErrorDuringRead, ex);
            }
        }


        private IMySqlValue GetFieldValue(int index, bool checkNull)
        {
            if (index < 0 || index >= FieldCount)
                Throw(new ArgumentException(Resources.InvalidColumnOrdinal));

            IMySqlValue v = resultSet[index];

            if (checkNull && v.IsNull)
#if NETSTANDARD1_3
                throw new MySqlNullValueException();
#else
                throw new System.Data.SqlTypes.SqlNullValueException();
#endif

            return v;
        }


        private void ClearKillFlag()
        {
            // This query will silently crash because of the Kill call that happened before.
            string dummyStatement = "SELECT * FROM bogus_table LIMIT 0"; /* dummy query used to clear kill flag */
            MySqlCommand dummyCommand = new MySqlCommand(dummyStatement, connection);
            dummyCommand.InternallyCreated = true;
            try
            {
                dummyCommand.ExecuteReader(); // ExecuteReader catches the exception and returns null, which is expected.
            }
            catch (MySqlException ex)
            {
                if (ex.Number != (int)MySqlErrorCode.NoSuchTable) throw;
            }
        }

        private void ProcessOutputParameters()
        {
            // if we are not 5.5 or later or we are not prepared then we are simulating output parameters
            // with user variables and they are also string so we have to work some magic with out
            // column types before we read the data
            if (!driver.SupportsOutputParameters || !command.IsPrepared)
                AdjustOutputTypes();

            // now read the output parameters data row
            if ((commandBehavior & CommandBehavior.SchemaOnly) != 0) return;
            resultSet.NextRow(commandBehavior);

            string prefix = "@" + StoredProcedure.ParameterPrefix;

            for (int i = 0; i < FieldCount; i++)
            {
                string fieldName = GetName(i);
                if (fieldName.StartsWith(prefix))
                    fieldName = fieldName.Remove(0, prefix.Length);
                MySqlParameter parameter = command.Parameters.GetParameterFlexible(fieldName, true);
                parameter.Value = GetValue(i);
            }
        }

        private void AdjustOutputTypes()
        {
            // since MySQL likes to return user variables as strings
            // we reset the types of the readers internal value objects
            // this will allow those value objects to parse the string based
            // return values
            for (int i = 0; i < FieldCount; i++)
            {
                string fieldName = GetName(i);
                fieldName = fieldName.Remove(0, StoredProcedure.ParameterPrefix.Length + 1);
                MySqlParameter parameter = command.Parameters.GetParameterFlexible(fieldName, true);

                IMySqlValue v = MySqlField.GetIMySqlValue(parameter.MySqlDbType);
                if (v is MySqlBit)
                {
                    MySqlBit bit = (MySqlBit)v;
                    bit.ReadAsString = true;
                    resultSet.SetValueObject(i, bit);
                }
                else
                    resultSet.SetValueObject(i, v);
            }
        }

        private void Throw(Exception ex)
        {
            if (connection != null)
                connection.Throw(ex);
            throw ex;
        }

        public new void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        internal new void Dispose(bool disposing)
        {
            if (disposing)
            {
                Close();
            }
        }

#region Destructor
        ~MySqlDataReader()
        {
            Dispose(false);
        }
#endregion
    }
}
